Résumé : Investigating the humoral immune response to mucosal antigens in patients with lung cancer, we have documented a preferential immunoglobulin G (IgG) binding to cryptic epitopes unmasked by the proteolysis of bovine beta-lactoglobulin (BLG). In contrast, IgG from healthy controls and patients with chronic bronchitis (COPD) bind preferentially to continuous epitopes presented on both native (n) and denaturated (d) forms of this antigen. The present study further characterized the differences in the epitope profiles recognized on BLG.